Crash at Plett airport (SF25 on 2 Dec 2019)

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Volo
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Re: Crash at Plett airport.

Unread post by Volo » Tue Dec 03, 2019 3:02 pm

John Boucher wrote:
Tue Dec 03, 2019 2:13 pm
I do not have any info but I do know this operation was approved as commercial flown by commercial pilots & was not associated with the Soaring Society in any way, I think it was CAA approval not RAASA approval - it was different.
I think I answered that in a previous post. Indeed they are fully compliant with the required ASL, Part 96 approval and yes NOT RAASA but CAA. A legitimate operation all the way after having jumped through all the hoops and requirements - contrary to what is thought!
..................
Their original part 96 operation was issued by the CAA back in 2006.
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Re: Crash at Plett airport.

Unread post by 117 » Tue Dec 03, 2019 3:40 pm

spokes wrote:
Tue Dec 03, 2019 11:57 am
The wind was on 30 yesterday. The aircraft came to rest left of the centreline and before the threshold on the eastern side of that little dam.
It is faceing the way it came plus a little bit more. To me it looks like a 270deg left spin on very short finals.
Was he doing a left or right turn onto finals for 30? I would guess a right turn and spun in to the right. (only looking at the right wing in the pics as we cant see the left)
spokes wrote:
Tue Dec 03, 2019 11:57 am
That airbrake still comes to mind.
I'm not sure what you mean, but I guess its along the lines of one airbrake (lets call it a spoiler rather) is deployed that we can see in the pics? The spoilers have a spring loaded system to close them, so any mechanical failure in the rigging to deploy it will ensure the spoiler stays closed. Besides, those spoilers are barely big enough to do their job on the falke, meaning assymetrical deployment should have little or no effect that the big barn door rudder cannot over power or correct.
spokes wrote:
Tue Dec 03, 2019 11:57 am
Nobody spins on short finals. IMHO. I may have my facts wrong
With long wings, this is a certain eventuallity you dont want to be in. Much like the dreaded turn for EFATO in a fixed wing, this too is a killer.

Lets paint a scenario, based on some assumptions so far:

- established on base leg with no engine on (nothing strange here, this is a motor glider after all)
- With the gusting wind and rubbish glide angle the falke has, the nose was pushed down to increase the air speed on base leg to make the fence
- lowish turn onto finals with the string (if it had one) too far in of a right skidding turn (ie: wings level-ish while over ruddering due to height above ground)
- wing drops due to over ruddering, pick it up with left opposite aileron (initiating adverse yaw to the right - which is already over ruddered)
- over it goes into a spin at low altitude

I assume the falke hit the deck at +- 30 to 40 deg nose down angle with the right wing taking some of the beating (pic from PO). I guess in this state, the short coupled nose will dump that motor onto the occupants laps in flash. In other words, they got caught under the firewall/motor - this would make sense with the rescue teams cutting them out shown in the pics

Sad none the less
Last edited by 117 on Tue Dec 03, 2019 4:11 pm, edited 1 time in total.
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Re: Crash at Plett airport.

Unread post by Jack Welles » Tue Dec 03, 2019 4:05 pm

Volo wrote:
Tue Dec 03, 2019 3:02 pm
John Boucher wrote:
Tue Dec 03, 2019 2:13 pm
I do not have any info but I do know this operation was approved as commercial flown by commercial pilots & was not associated with the Soaring Society in any way, I think it was CAA approval not RAASA approval - it was different.
I think I answered that in a previous post. Indeed they are fully compliant with the required ASL, Part 96 approval and yes NOT RAASA but CAA. A legitimate operation all the way after having jumped through all the hoops and requirements - contrary to what is thought!
..................
Their original part 96 operation was issued by the CAA back in 2006.
I didn't know the fellow and didn't know the operation but it seems to me that an awful lot of emphasis is being placed on the paperwork being in order (which is important, of course). He was also really well qualified as a pilot with extensive experience.

I was wondering about other aspects that may have eventually contrubuted to his having a prang, ie, whether the ops he carried out were always safe, as well. By this I mean, for example, did he ever fly very low level or did he do loops in an aerie marked as not for aerobatics etc? Did he ever take chances on the weather? Maybe when it was hectically windy etc?
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Re: Crash at Plett airport.

Unread post by Ugly Duckling » Tue Dec 03, 2019 4:08 pm

117
The other option is the spoiler was asymmetrical due to a cable snap & he chose to sideslip her onto finals, hit the turbulence and stalled/spun in.
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Re: Crash at Plett airport.

Unread post by Ugly Duckling » Tue Dec 03, 2019 4:11 pm

Jack Welles wrote:
Tue Dec 03, 2019 4:05 pm

I was wondering about other aspects that may have eventually contrubuted to his having a prang, ie, whether the ops he carried out were always safe, as well. By this I mean, for example, did he ever fly very low level or did he do loops in an aerie marked as not for aerobatics etc? Did he ever take chances on the weather? Maybe when it was hectically windy etc?
Ex SAAF & SAA with the Flying Lions Harvard & Pitts aerobatic teams. So yes he knew his aeros but having flown with him at Springs I would send my kids to fly with Stu.
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Re: Crash at Plett airport.

Unread post by p38 » Tue Dec 03, 2019 4:26 pm

117 wrote:
Tue Dec 03, 2019 3:40 pm

Lets paint a scenario, based on some assumptions so far:

- established on base leg with no engine on (nothing strange here, this is a motor glider after all)
- With the gusting wind and rubbish glide angle the falke has, the nose was pushed down to increase the air speed on base leg to make the fence
- lowish turn onto finals with the string (if it had one) too far in of a right skidding turn (ie: wings level-ish while over ruddering due to height above ground)
- wing drops due to over ruddering, pick it up with left opposite aileron (initiating adverse yaw to the right - which is already over ruddered)
- over it goes into a spin at low altitude


Sad none the less
Here is an example exactly how you describe it....
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Re: Crash at Plett airport.

Unread post by Ugly Duckling » Tue Dec 03, 2019 4:31 pm

p38 wrote:
Tue Dec 03, 2019 4:26 pm

Here is an example exactly how you describe it....
Windsock is showing his turn onto a tailwind
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Re: Crash at Plett airport.

Unread post by Clinton01 » Tue Dec 03, 2019 4:34 pm

[/quote]

Here is an example exactly how you describe it....

[/quote]

In this video there is a clear, relatively strong tail wind as can be seen with the windsock.

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Re: Crash at Plett airport.

Unread post by 117 » Tue Dec 03, 2019 4:35 pm

Ugly Duckling wrote:
Tue Dec 03, 2019 4:08 pm
117
The other option is the spoiler was asymmetrical due to a cable snap & he chose to sideslip her onto finals, hit the turbulence and stalled/spun in.
I doubt it Paul. Besides, landing without the spoilers is a non event. Especially if you have a nice head wind...

@ p38 - that windsock is showing a downwind turn. I doubt it was the case in this crash. But it does shown what I mean with the 30 to 40 deg nose down crash into terrain with the wing taking some punishment at the same time.
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Re: Crash at Plett airport.

Unread post by jimdavis » Tue Dec 03, 2019 4:49 pm

p38 wrote:
Tue Dec 03, 2019 4:26 pm
117 wrote:
Tue Dec 03, 2019 3:40 pm

Lets paint a scenario, based on some assumptions so far:

- established on base leg with no engine on (nothing strange here, this is a motor glider after all)
- With the gusting wind and rubbish glide angle the falke has, the nose was pushed down to increase the air speed on base leg to make the fence
- lowish turn onto finals with the string (if it had one) too far in of a right skidding turn (ie: wings level-ish while over ruddering due to height above ground)
- wing drops due to over ruddering, pick it up with left opposite aileron (initiating adverse yaw to the right - which is already over ruddered)
- over it goes into a spin at low altitude


Sad none the less
Here is an example exactly how you describe it....
P38 I would suggest the spin in the video is caused by the strong tailwind giving the pilot the illusion of adequate airspeed because the ground was going past at a good lick.

As far as I understand it the motor glider was approaching into wind so it was a very different situation.

And 117 I don't understand why you keep talking about over-ruddering. This is an extremely experienced, and current, aerobatic pilot who would be most unlikely to make a basic mistake like that.

jim
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Re: Crash at Plett airport.

Unread post by grounded » Tue Dec 03, 2019 5:05 pm

Ugly Duckling wrote:
Tue Dec 03, 2019 4:11 pm
Jack Welles wrote:
Tue Dec 03, 2019 4:05 pm

I was wondering about other aspects that may have eventually contrubuted to his having a prang, ie, whether the ops he carried out were always safe, as well. By this I mean, for example, did he ever fly very low level or did he do loops in an aerie marked as not for aerobatics etc? Did he ever take chances on the weather? Maybe when it was hectically windy etc?
Ex SAAF & SAA with the Flying Lions Harvard & Pitts aerobatic teams. So yes he knew his aeros but having flown with him at Springs I would send my kids to fly with Stu.
I have to wonder about the CAA's procedures and checklists for approving an AOC

If they DON'T ask the questions about flight profiles intended to be flown, with respect to minimum altitudes for gliding vs powered flight, then failure on their part of "keeping you safe in the skies" portion
if they DO ask the above question, and a DECLARED operational procedure, in the interest of keeping the paying public safe, is no engine out gliding below 500ft (for example), ie all approach and landings will be SAFELY exceuted under power....then SL's estate must brace itself for litigation.

Is the CAA's AOC approval procedure in depth enough to ask these safety related flight proile questions, or is it a tick-box excercise ?
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Re: Crash at Plett airport.

Unread post by Clinton01 » Tue Dec 03, 2019 5:13 pm

"ie all approach and landings will be SAFELY exceuted under power...."

Why would this be a requirement? It's a motorglider......

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Re: Crash at Plett airport.

Unread post by 117 » Tue Dec 03, 2019 5:18 pm

jimdavis wrote:
Tue Dec 03, 2019 4:49 pm


And 117 I don't understand why you keep talking about over-ruddering. This is an extremely experienced, and current, aerobatic pilot who would be most unlikely to make a basic mistake like that.

jim
Its the only cause i can think of to induce the spin so close to the ground in a long winged ship. Its pure speculation but going on the pictures of damage to the right wing, the forward swept final position of both wings when they came to rest, the flat looking fuz, the description by Spokes etc, leads me to believe this is a spin scenario. And i'm not reading into it, but that elevator sure looks like it is in a full up position.

Not criticizing the experience of the pilot at all Jim. Just looking at the facts available on this thread. My condolences if he was a close friend
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Re: Crash at Plett airport.

Unread post by jimdavis » Tue Dec 03, 2019 6:01 pm

117 wrote:
Tue Dec 03, 2019 5:18 pm
jimdavis wrote:
Tue Dec 03, 2019 4:49 pm


And 117 I don't understand why you keep talking about over-ruddering. This is an extremely experienced, and current, aerobatic pilot who would be most unlikely to make a basic mistake like that.

jim
Its the only cause i can think of to induce the spin so close to the ground in a long winged ship. Its pure speculation but going on the pictures of damage to the right wing, the forward swept final position of both wings when they came to rest, the flat looking fuz, the description by Spokes etc, leads me to believe this is a spin scenario. And i'm not reading into it, but that elevator sure looks like it is in a full up position.

Not criticizing the experience of the pilot at all Jim. Just looking at the facts available on this thread. My condolences if he was a close friend
Yep, I do agree have to agree with you 117 - it certainly looks like a spin. I would think the strong gusty wind was the bottom line. I live in the general area and that wind came out of nowhere. I suspect that the sudden gusts combined with the handbook's warning: In rough air the SF 25 C will drop a wing on stalling was just the wrong combination at the wrong time.

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Re: Crash at Plett airport.

Unread post by 117 » Tue Dec 03, 2019 6:16 pm

I thought it was a B version. But that aside the POH between the variants are pretty similar.

Dropping a wing at that height is never good in any aircraft. But gusts dont help either, sadly

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